War Surgery and Medicine
The most interesting observation, under this heading is the relatively large proportion of falciparum infections. This can be contrasted with almost complete absence of such infections among troops ceasing atebrin suppression after leaving the endemic area.
When we look into the monthly incidence of the various species of parasite it will be apparent that the big incidence of falciparum malaria was in October (22 cases) and November (10 cases). Nearly all these cases occurred on Vella Lavella during combat.
Allowing for an incubation period of two weeks, most of these infections were probably contracted after troops had been on atebrin for only about four weeks. It is now known that on the dosage of suppressive atebrin used the optimum atebrin blood level is not reached under six weeks. Probably most of these men who developed malaria at this time had an insufficiently high blood atebrin to suppress infection efficiently.
It is also now known that primary falciparum malaria is more difficult to suppress and requires high atebrin blood levels. So it is not surprising that this early predominance of falciparum cases should have occurred. It is significant, too, that most of the latent cases showed falciparum parasites in the blood, and these cases were also much more common in the earlier months. They are regarded as cases of primary falciparum infection in which the clinical symptoms are suppressed completely but not the parasitaemia. The final incidence of falciparum and vivax infections were approximately the same.